Everyone in the room had known for three days who the next archbishop of Canterbury would be. As we waited for Justin Welby, the thought occurred that if the Church of England had organised a press conference on the crucifixion, it wouldn't have been held until Easter Day.

We're told that constitutional convention had been responsible for the delay – the pope and Queen had to be told before the news could be confirmed. The pope, admittedly, is unlikely to have an account at Ladbrokes but the Queen, as a racehorse owner, was presumably told of the bookies' press releases that broke the news.

Constitutional convention also mostly stops archbishops from talking about Jesus in public. No one seems to have told this one. He entered the room to a remarkable lack of astonishment, a lean and rather severe figure, dressed in plain black but for a clerical collar and an unadorned silver pectoral cross. He started with a silent prayer, and went on to a short spoken one.

Then it was time to watch his famous technique of management by self-deprecation in action. He praised his predecessor as "one of the greatest archbishops of Canterbury, a man of integrity and holiness, and great moral and physical courage". The only comparison he would make with himself was that "I've got a better barber and I spend more on razors".

He praised most of the defeated candidates by name, but not all at once, and always for things they had done in their own diocese. Each one would have heard his own work praised and appreciated without it being obvious that there was any element of condolence involved. And when he wasn't praising bishops, or Roman Catholics (his spiritual director is a Benedictine monk) he was praising the ordinary clergy: "I have never had demands on me as acute as when I was a parish priest." This is very likely true.

But underneath the smooth was steel. Where other bishops might have blethered about how much the church had to offer the country, or quoted the sociologists who say how much social capital the church contributes, Welby gave a number. There are 22m hours of voluntary service performed outside the church by Christians each month, he said.

Of his own "worldly" background, he said: "Worldly in Christian terms is a very loaded word" – and not something any good Christian should want to be. The key thing he had got from his career in the oil industry was "the sense of having lived and worked in a world where the church is felt to be completely irrelevant".

He was very careful to praise both the church in Nigeria, which was for many years the leading opponent of accepting gay people, and the Episcopal church of the US, which was its chief proponent. The Americans "are people I love and value". Nigeria is "a country dear to my heart". But he said these things in such a matter-of-fact manner that they sounded as if they might be perfectly true. There are a few other bishops who can talk with this lack of churchiness, as if loving people were a perfectly normal thing to do, but Welby is the first to have been pushed on to the national stage.

He said he did not want Christians to agree with one another, "but to love one another and to demonstrate to the world around us a better way of disagreeing". Judging by the last 2,000 years or so, this is a rather more ambitious plan than merely reconverting England – but he seemed entirely serious about it. This could be interesting.